Distribution and concentration of cholesteryl ester transfer protein in plasma of normolipemic subjects.
A MAb (TP-2) directed against human cholesteryl ester transfer protein (CETP) has been applied to the development of a competitive solid-phase RIA. Experiments with immobilized CETP have shown that upon incubation with plasma or HDL in the presence of Tween (0.05%) apo A-I (but not apo A-II) binds to CETP while TP-2 binding to CETP is concomitantly decreased. With high detergent concentration (0.5% Triton), the interference is eliminated and a specific RIA in which all plasma CETP fractions have the same affinity can be obtained. Plasma levels of CETP, apo A-I, lipids, and lipoproteins were measured in 50 normolipemic, healthy subjects of both sexes. CETP levels varied nearly fourfold with a mean value of 1.7 micrograms/ml. CETP was positively correlated only with apo A-I (r = 0.38) and HDL-triglyceride (r = 0.39). In 29 other normolipemic subjects, where several apolipoproteins were also measured, significant correlations of CETP with apo A-I (0.41), apo E (0.43), and HDL-cholesterol (0.41) were observed, but there was no significant relationship between CETP and either apo A-II, B, or D. In other experiments CETP was shown to be present mostly in HDL3 and VHDL, to display exclusively an alpha 2-electrophoretic migration, and to occur within discrete particles ranging in size from 129 to 154 kD. In conclusion, the association of CETP with apo A-I-containing lipoproteins probably explains the correlation between CETP and apo A-I levels. The relationship between CETP and apo E suggests either a common metabolism or a specific cooperative role in cholesterol ester transport for these proteins.
Marcel
Y L
YL
Laboratory of Lipoprotein Metabolism, Clinical Research Institute of Montreal, Quebec, Canada.
McPherson
R
R
Hogue
M
M
Czarnecka
H
H
Zawadzki
Z
Z
Weech
P K
PK
Whitlock
M E
ME
Tall
A R
AR
Milne
R W
RW
D000328:Adult; D000911:Antibodies, Monoclonal; D001053:Apolipoproteins / Q000097:blood; D002352:Carrier Proteins / Q000097:blood*; D053480:Cholesterol Ester Transfer Proteins; D002788:Cholesterol Esters / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D006023:Glycoproteins; D006801:Humans; D015151:Immunoblotting; D008970:Molecular Weight; D011863:Radioimmunoassay / Q000379:methods; D012016:Reference Values; D014280:Triglycerides / Q000097:blood
D000911:Antibodies, Monoclonal; D001053:Apolipoproteins; C506642:CETP protein, human; D002352:Carrier Proteins; D053480:Cholesterol Ester Transfer Proteins; D002788:Cholesterol Esters; D008076:Cholesterol, HDL; D006023:Glycoproteins; D014280:Triglycerides